Need advice with dgpu

Hi all, I did successfully perform a vanilla install of Mac Mojave a while back but had to go back to windows after a HDD failure and I am looking at giving it another go but I am stuck on how to have it set up, I currently have a gtx 1060 which I know works fine in high Sierra and Windows, I did also buy a lower spec GT card that worked in Mojave, now from what I have seen it is impossible to have both gtx and GT cards installed at same time with windows using the gtx 1060 and Mac using the GT card, is this correct? Now I don't really want to use the GT card solely had it is a low spec card just to run Mojave so I just need some advice on options,

Do I /Can I use both cards (gtx - Windows) (GT - Mac)? Do I /Can I use one card (gtx - Windows) and Igpu for Mac? Scrap idea for Mojave and just stick with High Sierra (is there any major benefits of Mojave over High Sierra)?

Sorry if this is alot and eventually I will upgrade to a amd card I just need to work with what I have for the moment.